Assessing the effect of a barrier between two rooms subjected to low frequency sound using the boundary element method

The boundary element method (BEM) has been used to compute the acoustic wave propagation through a single vertical panel, which separates two rooms, made of concrete, when one of the rooms is excited by a steady-state, spatially sinusoidal, harmonic line load pressure at low frequencies. This work focuses on how the connection of the panel to the ceiling affects the acoustic insulation provided by the wall. Perfect double-fixed partitions and acoustic barrier-type structures with differently-sized gaps between the ceiling and the barrier are studied. The BEM model is formulated in the frequency domain and takes the air-solid interaction fully into account. Insulation dips are localised in the frequency domain and identified with dips associated with both the wall's natural dynamic vibration modes and with those associated with the air in the rooms. The influence of the wall's thickness on acoustic insulation is also analysed. The computed results obtained with the acoustic barrier type structure are compared with those obtained by a rigid model. The importance of the rooms' surface conditions is assessed, modelling the rooms with cork.